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Not the shade of blue

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angora831:
I have looked back in the ABC Forum for the topic of blue egg color.  I am looking for the genetics of the blue egg color and don\'t want to get into the discussion of what shade of blue we need for the breed.  What I found from other sources is that the blue color in eggshells is dominant to both brown and white.  When a blue is crossed with brown both contribute to the color of the eggshell and any shade of green, olive, etc can occur.  I also know that the brown color can have up to 13 other modifiers working on it\'s  shade and it has been suggested that white shells may also have these modifiers at work since there are several shades of white.  What I did not find mention of was the fact that these modifiers could also be at work on the blue gene present in our breed.
I doubt that it is this easy but, if we are getting eggs from our birds that have any tint of green/brown in them, does it then follow that our birds are not homozygous for the blue gene?  If this is true and we were to breed two hetrozygous birds together we would get a 1:2:1 ratio for the chicks in the F1 generation and work from there to rid the line of any brown influence?  Probably not that simple, eh?

Ken

Mike Gilbert:

--- Quote from: angora831 ---I doubt that it is this easy but, if we are getting eggs from our birds that have any tint of green/brown in them, does it then follow that our birds are not homozygous for the blue gene?  If this is true and we were to breed two hetrozygous birds together we would get a 1:2:1 ratio for the chicks in the F1 generation and work from there to rid the line of any brown influence?  Probably not that simple, eh?
--- End quote ---


Right on, it is not that simple.  The O gene responsible for blue shell coloration is inherited independently from the modifiers.  That means the modifiers work WITH the O gene to express any particular shade of color.  It is a blend, not one or the other.   Since there are so many modifiers, some being dominant, some recessive, it takes years of selection pressure to establish a line that always lays true blue eggs.
And there are so many other important things to select for that I don\'t know as that is practical.  If I were to start over again (some 35 plus years later) I would use only white egg chickens to develop the various colors, and worry about the ear lobe color later.   There are very few chicken breeds with red lobes that lay white eggs.   The black Crevecoeur is one, the Holland is another - if you can find them.   Hindsight is always 20-20, but the disqualification for white in lobes does not seem so important compared with the trials of establishing a line that lays only true blue eggs.   Here is a link that explains the blue shell chemistry.
http://ps.fass.org/cgi/reprint/85/3/546.pdf

jerryse:
I agree with Mike.White eggs are the only way to totally remove green from the breed.I also would  use white eggs if I were to start over.

angora831:
I was just trying to get my head around the genetics of the trait.  That is all, nothing more.  I agree that there are so many other things to work on to improve the breed.  I like the saying that I read somewhere... build the barn first and then paint it.   Pretty wise man there.

Ken

John:
For those of you that like analogies...
I look at it as if blue and white are the only two egg shell colors and they are like vinyl siding on a house.  The vinyl is the same color outside, inside and thru.  A pure white or blue egg shell is the same way when no brown modifiers are added.
I think of all those modifying shades of brown like latex paint.  It doesn\'t penetrate much like oil based paints, but it\'s just a covering on the outside.  Of course if you put latex paint on the outside of the vinyl siding it will make white siding look tinted or some darker shade of brown depending on both the shade of paint and how thick it\'s applied.  That layer of latex on the outside will make the inside color of the siding or shell look a different shade also.
About the only difference with blue eggs is the brown coating combines with the blue to make the eggs look some shade of  green instead of brown.  
When the inside and outside of a dry shell are the same color of blue or white I believe you have an egg without any of those many brown modifiers.
That\'s the color I\'ve selected for, but maybe a little \"tint\" added to the blue is really desirable.  It may not be \"pure\", but it sure is a prettier blue.
 

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